This article describes the dynamics of a manipulator with two degrees of freedom, while the dynamic model of the manipulator’s arm is derived using Lagrangian formalism, which considers the difference between the kinetic and potential energy of the system. The compiled dynamic model was implemented in Matlab, taking into account the physical parameters of the manipulator and friction term. Physical parameters were exported from the 3D CAD model. A scheme (model) was compiled in the Simulink, which was used for the subsequent validation process. The outputs of the validations were compared with measured data of joint angles from the system (expected condition) obtained by using gravity tests. For obtaining better results were parameters of the model optimizing by using the Trust Region Algorithm for Nonlinear Least Squares optimization method. Therefore, the aim of the research described in the article is the comparison of the model with the parameters that come from CAD and its improvement by estimating the parameters based on gravitational measurements. The model with estimated parameters achieved an improvement in the results of the Normal Root Mean Square Error compared to the model with CAD parameters. For link 1 was an improvement from 28.49% to 67.93% depending on the initial joint angle, and for link 2, from 63.84% to 66.46%.

The paper describes the validation of a dynamic model of a planar robotic arm using gravity tests. The drive of the arm (fluid muscles from the manufacturer Festo) was not activated during gravity tests (for the test was used only gravitation of solid). The measured data were obtained under the conditions that the joint angle was from 20° to 40°, the measurements were performed 10 times for each angle and at the same time independent for both links. The dynamics simulation was performed in the MATLAB® and Simulink environment, using the created simulation scheme, which presented the dynamics of the manipulator's arm with the inclusion of the friction component. The simulation results were compared with the measured data using two criteria (MAE -Mean Absolute Error and Fgof -Goodness of Fit).

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Current efforts are focused on assembling new constructions while applying non-conventional actuators, for example, artificial pneumatic muscles, in engineering manufacturing processes. The reason is to eliminate stiffness and inflexibility of equipment structures that make sharing the working space of the technological equipment complicated. This article presents the results of experimental measurements of pressures in artificial muscles and rotations of the actuator with artificial muscles at various loads, using a testing device of an antagonistic actuator. The measurement results were used to create the function of the course of the static property of the antagonistic actuator with artificial muscles of the Festo type and to determine a mathematical model of the actuator dynamics, while applying the method of least squares.

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